VOLCANOESVOLCANOES

Lava & MagmaLava & Magma

Lava vs. Magma…What’s the Lava vs. Magma…What’s the difference?difference?

Lava- magma that flows into Lava- magma that flows into Earth’s surface; the rock that forms Earth’s surface; the rock that forms when magma cools & solidifies.when magma cools & solidifies.

Magma- liquid rock produced Magma- liquid rock produced under the Earth’s surface.under the Earth’s surface.

Major Volcanic ZonesMajor Volcanic Zones

1.1. Subduction Zone- one tectonic plate moves under Subduction Zone- one tectonic plate moves under another. another.

-deep trenches form-deep trenches form-island arcs form -island arcs form

2.2. Mid-Ocean Ridges- plates pulling apart from one Mid-Ocean Ridges- plates pulling apart from one another. another. -Produces the most magma from -Produces the most magma from underwater volcanoes. underwater volcanoes.

-Mid-Atlantic Ridge and Iceland are examples.-Mid-Atlantic Ridge and Iceland are examples.

3.3. Hot Spots- happen with the interior of plates. Hot Spots- happen with the interior of plates. -example = Hawaiian islands-example = Hawaiian islands-made by mantle plumes-made by mantle plumes

Where volcanoes formWhere volcanoes form

Subduction Zones

Mid Ocean Ridges

Hot Spots

Hot SpotsHot Spots

Types of MagmaTypes of Magma

1.1. MaficMafic-made up of magnesium and iron-made up of magnesium and iron-dark in color-dark in color-oceanic and continental crust-oceanic and continental crust

2.2. FelsicFelsic-made up of silicates-made up of silicates-lighter in color-lighter in color-continental crust-continental crust

Types of EruptionsTypes of Eruptions

1.1. Quiet EruptionsQuiet Eruptions-mafic magma-mafic magma-oceanic volcanoes (Hawaii)-oceanic volcanoes (Hawaii)-low viscosity-low viscosity

2.2. Explosive EruptionsExplosive Eruptions-felsic magma-felsic magma-continental volcanoes-continental volcanoes-high viscosity-high viscosity-throw off large amounts of -throw off large amounts of

pyroclastic materialpyroclastic material

STRUCTURE

• Tephra (pyroclastics) – ash and rock ejected from a volcano.

•Vent – conduit or pathway for magma.

• Strata – layers of rock.

• Magma chamber – storage place for magma.

LAVALAVA

LAVALAVA

PahoehoePahoehoe

AAAA

Pillow LavaPillow Lava

Tephra (pyroclastic Tephra (pyroclastic material)material)

Volcanic Ash – the Volcanic Ash – the smallsmall stuffstuff

Volcanic Ash is small, but it is the most deadly.

Volcanic BlocksVolcanic Blocks

Volcanic BombsVolcanic Bombs

Types of VolcanoesTypes of Volcanoes1. Shield – Broad at the base, gently sloping sides, quiet eruptions, largest volcanoes. (Exp- Hawaiian Islands.)

2. Cinder Cone – Explosive eruptions, very steep slopes, only a few 100 meters high.

3. Composite of Stratovolcano – Explosive eruptions, pyroclastic flows can be deadly, very large volcanoes. (Exp- Mt. St. Helens, Mt. Pinatubo)

TYPES OF VOLCANOESTYPES OF VOLCANOES

CINDER CONECINDER CONE

CINDER CONE CINDER CONE

SHIELD VOLCANOSHIELD VOLCANOMauna Kea, HawaiiMauna Kea, Hawaii

SHIELDSHIELD

COMPOSITE VOLCANOCOMPOSITE VOLCANOMt. FujiMt. Fuji

Craters & CalderasCraters & Calderas

Crater- opening of the volcano where magma and or pyroclastic material is released.

Caldera- when the magma chamber of a volcano empties and collapses on itself.

CRATERCRATER

CRATERCRATER

CALDERACALDERA

Crater Lake in Oregon Crater Lake in Oregon Mt. MazamaMt. Mazama

EXTRATERRESTRIAL EXTRATERRESTRIAL VOLCANOESVOLCANOES

VOLCANOES FOUND ON MARS, IO (MOON OF JUPITER), OUR OWN MOON

MARS – OLYMPUS MONS, 28 KM ABOVE THE SURFACE, 600 KM ACROSS, CALDERA IS 70 KM ACROSS.

IO – ACTIVE VOLCANOES ON SURFACE (FIRST PLANETARY BODY TO HAVE ACTIVE VOLCANOES)

MOUNT ST. HELENS

MT. ETNAMT. ETNA

Predicting Volcanic Predicting Volcanic EruptionsEruptions-changes in earthquake activity around -changes in earthquake activity around

an earthquake.an earthquake.-increase in pressure of the surrounding -increase in pressure of the surrounding

rocks.rocks.-temperature changes-temperature changes-fracturing of rock-fracturing of rock-sections of the volcano may bulge-sections of the volcano may bulge

The End!The End!